This invention concerns improved arthroscopic surgical instruments.
The effective use of powered instruments for arthroscopically cutting and shaping tissues within a joint dates from an invention which I helped create (U.S. Pat. No. 4,203,444, issued May 20, 1980). Such instruments are now in wide use. As skills have advanced, surgeons have desired more aggressive and faster acting instruments, and instruments suitable for an expanded range of tasks. Prior individual instruments, however, have usually been suited for only one or a rather limited number of functions because of the differences in tissue to be removed. These tissues vary from hard to soft, firmly attached to very mobile, and easy to approach to difficult and awkward of access.
Not only is the changing of instruments time consuming, but also each change increases the probability of scuffing or otherwise injuring healthy tissue as the various arthroscopic instruments are slid in and out of the joint. The present invention provides an arthroscopic instrument capable of removal of a wide variety of tissues. This not only decreases the risk of inadvertent scuffing, etc., but also increases the speed of the procedure. This swiftness can avoid physician fatigue, minimize anesthesia time for the patient, and increase the number of procedures possible with a given operating room facility.
The invention, in common with prior powered instruments, employs an outer stationary member sized to enter the joint through a puncture opening. The outer member has at least one distal aperture at which the wall of the outer member defines a first, fixed blade surface terminating in a cutting edge. An internal movable member, disposed within the outer member and adapted to be power driven, has a second cutting edge arranged to move toward and closely past the fixed cutting edge in rapid, repetitive fashion to sever tissue. The movable member has an associated drive means which repeatedly moves the second cutting edge in this cutting direction.
According to one aspect of the present invention, an improvement lies in the provision of a table extension at the aperture, projecting outwardly from the general contour of the body of the outer stationary member, the extension constructed and arranged to engage tissue against which the operator urges the instrument, in a manner to improve the repetitive cutting action.
In preferred embodiments of the invention, the table extension projects in retrograde manner with an outward component and a component of projection in the direction opposite to the direction of cutting movement of the inner member; the aperture is provided in the side wall of the outer member, and the table extension projects outwardly beyond the general outer side surface of the outer member in the vicinity of the aperture, preferably a blade surface that corresponds to the thickness of the side wall of the outer member lies at a retrograde angle to a radius from the axis of movement of the inner member projected through the first cutting edge and the table extension lies at a greater angle to the radius, and preferably the table extension projects outward from the general contour of the outer surface of the outer member by at least 20% of the thickness of the general side wall of the outer member; the table extension projects outward by at least the order of the thickness of the general side wall, preferably the table extension projects from the blade surface by at least the order of the thickness of the general side wall of the outer member; the table extension projects in a retrograde manner from the blade surface by at least 20% of the thickness of the general side wall of the outer member, preferably the table extension projects from the blade surface by at least the order of the thickness of the general side wall of the outer member; the instrument includes a notch provided in the region of intersection between the proximal end of the table extension and the general side wall of the outer member; the outer member is generally circular in transverse cross section and is tapered distally in a region proximal of the aperture; the outer member at opposite sides of the aperture defines a pair of first, fixed cutting edges, the movable member adapted to move selectively in opposite directions and defining a pair of second cutting edges each adapted to coact with a respective cutting edge of the first pair, and there being a table extension associated with each fixed cutting edges, preferably the inner cutter has two cutting edges that provide cutting points arranged in a different pattern so that points on one edge are staggered longitudinally from any point on the other edge, preferably each table extension surface extends outwardly to at least a line projected tangent to the path of a second cutting edge at its midpoint between first cutting edges, and preferably the table extension has an outer surface disposed generally on or within a line projected tangent to outer surface of the outer member at the radius of the path of travel of the second cutting edge at 90.degree. after the midpoint; the cutter defines two apertures, and comprises at least one table extension at each aperture; the outer member comprises a tube having a generally cylindrical form; the table extension defines a tissue surface; and the outer member comprises a tube having a generally cylindrical form, the aperture is provided in the side wall of the tube, and the table extension projects outwardly beyond the cylinder projected through the outer surface of the tube in the vicinity of the aperture, the outer member at opposite sides of the aperture defines a pair of first, fixed cutting edges, the first fixed edges extending generally parallel to the axis of the tube, the movable member adapted to move selectively in opposite directions and defining a pair of second cutting edges each adapted to coact with a respective cutting edge of the first pair, and there being a table extension associated with each fixed cutting edge, each of the table extensions projecting generally outwardly from the edge surface with a component of extension in the direction opposed to the direction of cutting movement of the inner member, preferably a line projected between outermost tips of the pair of table extension lies substantially tangent to the path of travel of the inner cutting edges, preferably the tube has a diameter of 5 millimeters or less and the table extension projects outward from the general contour of the outer surface of the tube by at least 20% of the thickness of the general side wall of the tube, and preferably the table extension defines a tissue immobilizing surface.
According to another aspect of the invention, an arthroscopic surgical instrument comprises an outer stationary member sized to enter a joint through a puncture opening and having a distal aperture, the wall of the outer member at the aperture defining a first, fixed cutting edge, an internal movable member disposed within the outer member, the movable member having at least a pair of second cutting edges arranged to move sequentially toward and closely past the fixed cutting edge to sever tissue at a shearing point and adapted to be power driven for repeated, rapid movement of the second cutting edges in the cutting direction, each second cutting edge defining one or more cutting points arranged longitudinally along the second cutting edge, and a cutting point of one second cutting edge being offset longitudinally from a cutting point of the next following second cutting edge, whereby the sequential second cutting edges have different cutting patterns.
In preferred embodiments of this aspect of the invention, the outer member at opposite sides of the aperture defines a pair of first, fixed cutting edges, the movable member adapted to move selectively in opposite directions and defining pairs of second cutting edges, each pair of second cutting edges adapted to coact with a respective first cutting edge; and, due to asymmetric arrangement of the cutting points, the body of the inner member, in the area of the second cutting edges, is of substantially uniform axial section.
There is thus provided an instrument capable, in a majority of instances, of performing an entire arthroscopic surgical procedure, including, e.g., articular cartilage debridement, synovial resection, removal of osteophytes, plica resections and meniscectomies, normally performed in the past only by use of multiple instruments, with attendant increase in time, trauma, and risk of injury to healthy tissue in the joint.
These and other features and advantages of the invention will be apparent from the following description of the preferred embodiment, and from the claims.